Electromagnetic core-energy actuator

Abstract

An electromagnetic actuator device converts electrical energy to mechanical energy by the interaction of two types of closed magnetic circuits. A first closed magnetic circuit functions to generate high magnetic intensity in a portion of a ferromagnetic core. A second substantially-closed magnetic circuit contains a movable permanent magnet which injects flux into the high-field region of the first magnetic circuit. Interaction of these two fields, in closed magnetic circuits, results in efficient and controllable electromechanical energy conversion.

What is claimed is: 
     
       1. An electromagnetic device which realizes electromechanical energy conversion by changing the magnetic field energy internal to ferromagnetic linear or curved, bar-shaped members, the said internal field energy being changed by flux from the pole of a permanent magnet as it moves at a constant distance from, and along, a lateral surface of each bar, having an output force given by the equation,   f=H.sub.c φ.sub.m,     where f is force in Newtons, H c  is the internal magnetic intensity of the bar in Amperes per meter and φ m  is the flux entering the core from the magnet, and     comprising: a plurality of first magnetic circuits having no air gap, each consisting of a low-reluctance ferromagnetic core upon which is wound coil means for a source of magnetomotive force, in series with a ferromagnetic core having at least five-times greater reluctance, wherein a region of high magnetic field energy is generated by the said coil means and low-reluctance core combination,   second magnetic circuits, having one or more permanent magnets, with flux perpendicular to the flux of said ferromagnetic high-field-energy cores of said first magnetic circuits, said permanent magnets being constrained to move in paths such that at least one pole travels close to, and at a constant distance from, a lateral surface of said ferromagnetic high-field-energy cores of said first magnetic circuit, thereby forcing additional flux into the said region of high magnetic field energy, said flux being returned by the low-reluctance path of the said first magnetic circuit, said additional flux combining within the said region to produce magnetic field energy changes which generate useful force output on the movable said permanent magnets, which may be transmitted to mechanically-attached members, such as a journaled output shaft, and   adjustable or fixed mechanical stops, consisting of three respective layers of tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnets.     
     
     
       2. The electromagnetic device of claim 1, wherein said permanent magnet(s) have mechanically-opposed magnetic poles and opposing said regions of high magnetic field energy, such that lateral tractive magnetic forces between the said poles and the said high-field-energy cores are cancelled and bearing frictional losses are minimized. 
     
     
       3. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are linear. 
     
     
       4. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are circular rings or portions thereof and said permanent magnets have said poles which move along an inside diameter of the said rings. 
     
     
       5. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are circular washers or portions thereof and said permanent magnets have said poles which move along the lateral surfaces of the said washers. 
     
     
       6. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are circular double helices and said permanent magnets have said poles which move in helical paths along the inside diameter of the said double helices. 
     
     
       7. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are circular double helices and said permanent magnets have said poles which move in helical paths between the lateral sides of the coils formed by the said double helices. 
     
     
       8. The electromagnetic device of claim 1, further comprising: a linear Hall sensor and   two ferromagnetic strips, half the length of the said core, approximately 0.8 mm thick and of width equal to the said core;   wherein the strips are formed and mounted in close proximity, <0.25 mm, one to each half of a lateral surface of a said high-energy core, each strip having a protruding portion formed perpendicularly outward from, and centrally located with respect to, the lateral surface of the said high-energy core, defining a space between said portions sufficient for receiving the Hall sensor, for the purpose of monitoring magnetic leakage flux of the said core, and thereby determining the magnetic state and corresponding said permanent magnet/armature position.   
     
     
       9. The electromagnetic device of claim 1, further comprising: a coil of thin wire, of material such as insulated copper, less than 0.3 mm diameter;   wherein the said wire is progressively wound in a single layer on the surface of a said high-energy core, and is chosen to be of small diameter, less than half the gap between a said magnet pole and the cooperating said high-energy field core;   for the purpose of generating a Voltage at the said coil terminals proportional to the velocity of a said permanent magnet, magnitude and polarity being given by Faraday's law of induction.   
     
     
       10. The electromagnetic device of claim 1, wherein material having high magnetic hysteresis losses is used for the said ferromagnetic high-energy cores, to provide mechanical braking and/or maintain the position of said permanent magnets when electrical power is removed. 
     
     
       11. The electromagnetic device of claim 1, further comprising: a thick conductive strip or a coil of insulated wire, of material such as copper, with finished thickness dimension greater than 0.5 mm;   Wherein the said conductive strip or coil is wrapped around a fraction of the length of a said high-energy core at the position(s) where damping is desired, and when electrically shorted, will have electrical current due to Voltage induced by the motion of a said permanent magnet and the associated flux, magnitude and polarity being given by Faraday's law of induction, and will produce, according to Lenz's Law, a force opposing the original motion, that is, a damping force, when flux from the said magnet is at the location of the electrically-shorted said strip or coil.   
     
     
       12. The electromagnetic device of claim 1, wherein the cross-sectional area of a said ferromagnetic high-energy core varies along the length, the varying cross-sectional area resulting in inverse variation in magnetic reluctance, resulting in a corresponding inverse variation in magnetic intensity H c  and, since actuator output force or torque is directly proportional to magnetic intensity H c , an inverse variation in output; thus modifying or tailoring the actuator force/torque versus position to match mechanical load requirements. 
     
     
       13. The electromagnetic device of claim 1, wherein the surface contour of a said ferromagnetic high-energy core varies along the length. The varying surface contour, being adjacent to the path of the pole of a said permanent magnet, will vary magnet flux, a wider gap resulting in less flux and a shorter gap resulting in greater flux; since actuator output force or torque is directly proportional to said magnet flux, the output actuator force/torque versus position can be designed to match mechanical load requirements. 
     
     
       14. The electromagnetic device of claim 3, further defined by a rectangular cavity formed by parallel top and bottom horizontal rectangular bars, vertically-spaced and functioning as the said ferromagnetic high-field-energy cores,   a said permanent magnet, substantially bar-shaped, length-wise magnetized and having a north and south pole, with axis positioned vertically, constrained to move horizontally within the said rectangular cavity with said poles moving adjacent to the inside surfaces of the said rectangular bars, having an affixed output member, such as a journaled shaft,   said low-reluctance sources of magnetomotive force located at each end of the said rectangular bars, and   adjustable or fixed mechanical stops, of layered tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnet.   
     
     
       15. The electromagnetic device of claim 1, wherein the said sources of magnetomotive force, the said ferromagnetic high-field-energy cores and paths of said permanent magnets are located in the same plane. 
     
     
       16. The electromagnetic device of claim 1, wherein the said sources of magnetomotive force are located in a plane perpendicular to the plane containing the said ferromagnetic high-field-energy cores and paths of said permanent magnets. 
     
     
       17. The electromagnetic device of claim 1, wherein the said sources of magnetomotive force are located in a single plane parallel to the plane containing the said ferromagnetic high-field-energy cores and paths of said permanent magnets. 
     
     
       18. The electromagnetic device of claim 1, wherein the said sources of magnetomotive force are located in parallel planes on both sides of the plane containing the said ferromagnetic high-field-energy cores and paths of said permanent magnets. 
     
     
       19. The electromagnetic device of claim 4, further defined by a horizontal cylindrical cavity formed by top and bottom half-rings functioning as said ferromagnetic high-field-energy cores,   a said permanent magnet, substantially bar-shaped with north magnetic pole at one end and a south pole at the opposite end, constrained and of dimension small enough to rotate within the defined cylindrical cavity with said poles traversing an inside circular path adjacent to the inside diameter of the said cylindrical cavity, and affixed to a member, such as a cylindrical journaled shaft, for transmitting mechanical torque to an external load,   a said low-reluctance source of magnetomotive force in the form of a ferromagnetic half-ring, of inside diameter larger than the outside diameter of the said half-ring high-field-energy cores, having two diametrically-opposed internal salient poles for transmitting flux to the internal, smaller said half-ring high-field-energy cores and having coil means thereon for receiving electrical energy, and   adjustable or fixed mechanical stops, of layered tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnet.   
     
     
       20. The electromagnetic device of claim 1, further defined by a horizontal cylindrical cavity formed by a top half-ring, functioning as a said ferromagnetic high-field-energy core, and a ferromagnetic bottom half-ring, functioning as a said source of magnetomotive force and having a said coil means that not only receives electrical power but also produces force on an adjacent magnet pole, said bottom half-ring having an inside diameter equal to that of the said top half-ring, and a radial thickness at least two times greater than the said top half-ring,   a said permanent magnet, substantially bar-shaped with north magnetic pole at one end and a south pole at the opposite end, constrained and of dimension small enough to rotate within the said cylindrical cavity with said poles traversing an inside circular path adjacent to the inside diameter of the said cylindrical cavity, and affixed to a member, such as a journaled cylindrical shaft for transmitting mechanical torque to an external load.   
     
     
       21. The electromagnetic device of claim 5, further defined by a vertical cylindrical cavity formed by top and bottom, vertically-spaced horizontal washer-shaped segments of less than 360-degree angular length, and functioning as said ferromagnetic high-field-energy cores,   a said permanent magnet, substantially bar-shaped, length-wise magnetized and having a north and south pole, with axis positioned vertically, constrained and of dimension small enough to rotate within the vertical length of the defined cylindrical cavity with said poles moving along the inside top and bottom lateral surfaces of the washer-shaped segments, affixed by a radial arm to a central member located on the vertical axis, such as a journaled cylindrical shaft, for transmitting mechanical torque to an external load,   said low-reluctance sources of magnetomotive force in the form of similar, but at least two times thicker, washer-shaped circular segments located in horizontal parallel planes at the top and bottom of the assembly, spaced vertically from said ferromagnetic high-field-energy cores in order to accommodate coil means, and having salient poles at each segment end for transmitting magnetic flux to said ferromagnetic high-field-energy cores.   
     
     
       22. The electromagnetic device of claim 1, further defined by a plurality of linear actuator sections, constructed according to the present invention, wherein actuator sections have overlapping force-generating regions, to generate high force and long mechanical travel when actuator sections are energized in sequence; comprising: a rectangular cavity formed by parallel top and bottom horizontal rectangular ferromagnetic bars, vertically-spaced, each functioning as a plurality, N→2, of said high-field-energy cores,   a said permanent magnet, substantially bar-shaped, length-wise magnetized and having a north and south pole, with axis positioned vertically, constrained to move horizontally within the cavity, with said poles moving adjacent to the inside surfaces of the said bars, having an affixed output member, such as a journaled shaft,   a plurality, N, of said sources of magnetomotive force both above and below the said horizontal bars, each plurality having a central horizontal core similar to a said rectangular bar, but of at least two times thicker cross-section, and having N+2 equally-spaced salient poles for transmitting flux to a said rectangular bar, the poles producing sufficient vertical space to accommodate N+1 coil means (for receiving electrical energy) between the N+2 salient poles, and   adjustable or fixed mechanical stops, consisting of three respective layers of tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnet.   
     
     
       23. The electromagnetic device of claim 1, wherein said ferromagnetic high-energy cores are circular rings or portions thereof and said permanent magnets have said poles which move along an inside diameter of the said rings, further defined by a plurality of actuator sections, constructed according to the present invention, wherein actuator sections have overlapping torque-generating regions, to generate high torque and continuous angular motion when actuator sections are energized in sequence; comprising: a cylindrical cavity defined by the interior of a first ferromagnetic ring or tube, functioning as a plurality N=4n, where n=1, 2, . . . , of said high-field-energy cores,   2n said permanent magnets, substantially bar-shaped, length-wise magnetized and having a north and south pole, arranged radially with equal angular spacing and alternating poles, constrained to rotate within the defined cylindrical cavity with said alternating poles traversing an inside circular path adjacent to the inside diameter of the said cylindrical cavity, and affixed to an output member, such as ajournaled shaft, at the rotational axis,   a said plurality N of said low-reluctance sources of magnetomotive force spaced angularly around the outside diameter of the first ferromagnetic ring, consisting of a second circular ring-shaped ferromagnetic core of at least two times larger cross-section and larger inside diameter than the outside diameter of said first high-field-energy ring, having N salient poles, equally-spaced around the inside diameter, for transmitting flux to the central first high-field-energy core, and defining spaces to accommodate N said coil means (for receiving electrical energy) between the said N salient poles, and   adjustable or fixed mechanical stops, consisting of three respective layers of tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnet.     
     
     
       24. The electromagnetic device of claim 5, further defined by a plurality of actuator sections, constructed according to the present invention, wherein actuator sections have overlapping torque-generating regions, to generate high torque and continuous angular motion when actuator sections are energized in sequence; comprising: a vertical cylindrical cavity formed by top and bottom, vertically-spaced horizontal washer-shaped cores functioning as a plurality N=4n, where n=1, 2, . . . , of said ferromagnetic high-field-energy cores,   2n said permanent magnets, substantially bar-shaped, length-wise magnetized and having a north and south pole, with axes positioned vertically, equally-spaced angularly with alternating poles, constrained and of dimension small enough to rotate within the vertical length of the defined cylindrical cavity with said poles moving along the inside top and bottom lateral surfaces of the washer-shaped cores, affixed by radial arms to a central member located on the vertical axis, such as a cylindrical journaled shaft, for transmitting mechanical torque to an external load,   N said low-reluctance sources of magnetomotive force both at the top and bottom of the assembly, in the form of similar, but at least two times thicker washer-shaped circular ferromagnetic cores located in horizontal parallel planes, spaced vertically from said ferromagnetic high-field-energy cores in order to accommodate N coil means, and having N salient poles, equally-spaced angularly around the source washer interior lateral surface, for transmitting flux to the central high-field-energy cores, and   adjustable or fixed mechanical stops, consisting of three respective layers of tough, energy-absorbing and rigid materials, located at the extremities of travel of the said permanent magnet.